[Infectious mononucleosis: hemolysis by autoantibodies against triosephosphate isomerase]

Generalized adenopathy and splenomegaly developed in an 18-year-old youth after a severe tonsillitis followed by headache, tiredness and weight loss for several weeks. Infectious mononucleosis (acute Epstein-Barr virus infection) was confirmed by the demonstration of virus-specific antibodies. A reticulocytosis (24%), decreased haptoglobin concentration (0.6 mg/dl) and increased lactate dehydrogenase activity (657 U/l) indicated marked haemolysis. The bone marrow showed increased erythropoiesis with abnormal maturation. Antibodies against triosephosphate isomerase and against blood group marker "i" were demonstrated in the patient's serum. Antibodies against triosephosphate isomerase from the patient's serum were purified by affinity-chromatography. They strongly reacted with the patient's erythrocytes and under complement activation induced an increased 51Cr liberation from marked erythrocytes. No corresponding effect of anti-i-antibodies was noted at 37 degrees C. With the fall in antibodies against triosephosphate isomerase the haemolysis receded and the patient became free of symptoms after 7 weeks.